# 10.3: Group 5

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All group 5 metals are normally found in nature as oxide ores that contain the metals in their highest oxidation state (+5). Because of the lanthanide contraction, the chemistry of Nb and Ta is so similar that these elements are usually found in the same ores.

• Chemistry of Dubnium
Dubnium (Db) is a transactinide element and is highly radioactive. The most stable known isotope, dubnium-268, has a half-life of just above a day, which greatly limits the extent of possible research on dubnium. Dubnium does not occur naturally on Earth and is produced artificially.
• Chemistry of Niobium
Pure niobium looks much like steel but resists corrosion better due to a thin coating of oxide that forms on all exposed surfaces. The only acid that attacks Nb at room temperature is HF. Above 200° the metal becomes more reactive.
• Chemistry of Tantalum
Tantalum is a heavy, gray metal that resembles the more expensive platinum in many respects and is sometimes used as an economical substitute for that element. The metal comprises only 0.0002% of the earth's crust. Tantalum alloys are corrosion and wear resistant and find use in dental and surgical tools. Tantalum oxide is used in some electronic components and a composite of tantalum carbide (TaC) and graphite is one of the hardest materials ever produced.